In an electronic system, it is important to evaluate power consumption. The power consumption deeply affects both the unit price and quality of a product.
Conventionally, there have been proposed a method of calculating values of power of signal lines and values of power of logic cells (e.g. minimum units in logic synthesis, such as AND circuits and OR circuits) in a circuit to be evaluated, and then adding up these calculated values of power, to thereby calculate the overall dynamic power of the circuit.
The power of each signal line is determined e.g. by determining a change density D (the number of signal changes/second) of the signal in the signal line by logic simulation, and calculating ½×C (load capacity of the signal)×V (voltage)2×D.
Conventionally, there has been known a method of measuring the above-mentioned number of signal changes (the number of times a signal changes state) using a measurement circuit that is often used on an emulator. Further, to reduce the number of measurement circuits, there has also been known a method of counting the number of signal changes from a plurality of signal lines, using a single counter.
By the way, these days, scratch development has come to be planned less frequently. A system architect configures a system by properly combining black-box components, and evaluates whether the configured system achieves the performance, power consumption, and quality demanded by his client. Therefore, it is important to intuitively understand power (requirements or consumption) of the system, and hence there is a demand for a system-level power estimation covering a long time period.
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However, in the conventional power estimation method, it is difficult to accurately analyze a power consumption tendency covering a long time period (e.g. not shorter than the order of seconds) for a large-scale circuit.
The reason for this difficulty includes e.g. increases in the number of measurement circuits and the amount of measurement data, and an increase in time for power estimation. Further, if an easy measure, such as reduction of the number of signal lines to be observed, is taken, the accuracy of the power estimation lowers.